Perforating equipment for photographic films and papers, use chrome plated stainless steel or a hardened stainless steel as guide rails for conveying films to the feed chute for perforation. Precision perforation on the film edges is required to advance or rewind films in cameras and projection of movie films on the screen. The guide rails in a perforator guide the film edges during transportation into a perforator. The guide rails also locate the film precisely prior to perforation.
There are three guide rails in a typical perforator. The film edges rub against the guide rails at speeds of 100 to 300 feet per minute and create a groove on the chrome plated steel rails in a relatively short time. As the groove deepens with time, the guide rails need to be replaced to ensure the film edges are perfectly aligned under the perforator punches for perforation. Thin chrome plating generally provides an adequate hard, wear resistant surface which does not produce scratches on the film. Thick chrome plating, however, generates a rough surface and is not used on stainless steel guide rails, unless the plating is lapped to generate a smooth surface.
Moreover, photographic films contain corrosive silver halide salts and other additives which attack stainless steel through microcracks or pores in the chrome plating. The corrosion products along with the wear debris tend to contaminate the film which is being perforated.
The present invention replaces the chrome plated stainless steel guide rails with yttria tetragonal zirconia polycrystal ceramic rails. The ceramic rails are in many cases more cost effective and provide superior wear resistance and corrosion resistance than prior art chrome plated stainless guide rails. In addition, the absence of corrosion products and the reduction in wear debris helps reduce film contamination.